Devices and methods for cervix measurement

ABSTRACT

A device for measuring a length of a cervix includes an elongate measurement member, a hollow member, a flange, a handle, and a locking mechanism. The elongate measurement member extends along a longitudinal axis and includes a measurement scale thereon. The hollow member is coaxial with and disposed over the elongate measurement member. The flange is offset from the longitudinal axis and attached to a distal end of the hollow member. The handle is attached to a proximal end of the measurement member. The locking mechanism is configured, when locked, to fix the hollow member relative to the measurement member and, when unlocked to allow the hollow member to slide along the measurement member and rotate about the longitudinal axis so as to place the flange in a desired position without moving the measurement scale.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Patent ApplicationNo. 61/260,520, filed Nov. 12, 2009, entitled “Devices and Methods forCervix Measurement.” This application also claims priority to U.S.Provisional Patent Application No. 61/369,523, filed Jul. 30, 2010,entitled “Devices and Methods for Cervix Measurement.” Theseapplications are herein incorporated by reference in their entirety.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to medical devices and methods of usingsuch devices. More particularly, the invention relates to instrumentsand methods to measure the length of the cervix in the formix vaginaeand the dilation of the cervix uteri.

BACKGROUND OF THE INVENTION

Preterm labor, or labor before 37 weeks gestation, has been reported inapproximately 12.8 percent of all births but accounts for more than 85percent of all perinatal complications and death. Rush et al., BMJ2:965-8 (1976) and Villar et al., Res. Clin. Forums 16:9-33 (1994),which are both incorporated herein by reference. An inverse relationshipbetween cervical length in the formix vaginae and the risk of pretermlabor has also been observed. Andersen et al., Am. J. Obstet. Gynecol.163:859 (1990); tarns et al., N. Eng. J. M. 334:567-72 (1996) and Heathet al., and Ultrasound Obstet. Gynecol. 12:312-7 (1998), which all areincorporated herein by reference. Accordingly, many physicians find ituseful to examine the cervix in the formix vaginae as part of normalprenatal care in order to assess risk of preterm labor.

It has long been known that the cervix normally undergoes a series ofphysical and biochemical changes during the course of pregnancy, whichenhance the ease and safety of the birthing process for the mother andbaby. For example, in the early stages of labor the tissues of thecervical canal soften and become more pliable, the cervix shortens(effaces), and the diameter of the proximal end of the cervical canalbegins to increase at the internal os. As labor progresses, growth ofthe cervical diameter propagates to the distal end of the cervicalcanal, toward the external os. In the final stages of labor, theexternal os dilates allowing for the unobstructed passage of the fetus.

In addition to the physical and biochemical changes associated withnormal labor, genetic or environmental factors, such as medical illnessor infection, stress, malnutrition, chronic deprivation and certainchemicals or drugs can cause changes in the cervix. For example, it iswell known that the in utero exposure of some women todiethylstilbestrol (DES) results in cervical abnormalities and in somecases gross anatomical changes, which leads to an incompetent cervixwhere the cervix matures, softens and painlessly dilates withoutapparent uterine contractions. An incompetent cervix can also occurwhere there is a history of cervical injury, as in a previous traumaticdelivery, or as a result of induced abortion if the cervix is forciblydilated to large diameters. Details of the incompetent cervix arediscussed in Sonek, et al., Preterm Birth, Causes, Prevention andManagement, Second Edition, McGraw-Hill, Inc., (1993), Chapter 5, whichis incorporated by reference herein.

Cervical incompetence is a well recognized clinical problem. Severalinvestigators have reported evidence of increased internal cervical osdiameter as being consistent with cervical incompetence (see Brook etal., J. Obstet. Gynecol. 88:640 (1981); Michaels et al., Am. J. Obstet.Gynecol. 154:537 (1986); Sarti et al., Radiology 130:417 (1979); andVaalamo et al., Acta Obstet. Gynecol. Scan 62:19 (1983), all of whichare incorporated by reference herein). Internal os diameters rangingbetween 15 mm to 23 mm have been observed in connection with anincompetent cervix. Accordingly, a critical assessment in the diagnosisof an incompetent cervix involves measurement of the internal cervicalos diameter.

There are also devices and methods to measure the diameter of theexternal cervical os. For example, cervical diameter can be manuallyestimated by a practitioner's use of his or her digits. Although anindividual practitioner can achieve acceptable repeatability using thismethod, there is a significant variation between practitioners due tothe subjective nature of the procedure. To address these concerns,various monitoring and measuring devices and methods have beendeveloped. For example, an instrument for measuring dilation of thecervix uteri is described in U.S. Pat. No. 5,658,295. However, thisdevice is somewhat large, leading to a risk of injury to the fundus ofthe vagina or cervical os. Additionally, it is not disposable andrequires repeated sterilization. Another device for measuring cervicaldiameter is described, for example, in U.S. Pat. No. 6,039,701. In oneversion, the device described therein has a loop element which issecured to the cervix. The loop expands or contracts with the cervix anda gauge is coupled to the loop for measuring changes in the loopdimension. Such changes can then be detected by electronic means.Accordingly, this device is rather complex and expensive to manufacture.

Even if a woman is found to have an apparently normal internal cervicalos diameter, there may nonetheless be a risk for preterm labor anddelivery. Currently, risk assessment for preterm delivery remainsdifficult, particularly among women with no history of preterm birth.However, the findings that preterm delivery is more common among womenwith premature cervical shortening or effacement suggest that ameasuring the length of the cervix would be predictive for pretermlabor.

Currently, a physician has at least two options to measure the length ofthe cervix in the formix vaginae. One such method involves serialdigital examination of the cervix by estimating the length from theexternal cervical os to the cervical-uterine junction, as palpatedthrough the vaginal formix. Although this is useful for generalqualitative analysis, it does not afford an easy nor accuratemeasurement of the length of the cervix from the external cervical os tothe cervical-uterine junction (also described herein as the length ofthe cervix extending into the vagina) and, therefore, does not providean accurate assessment of the risk of preterm labor. Despite the use ofgloves, digital vaginal exams always carry with them the risk oftransmitting infectious agents, especially to the fetal membranes, thelining and/or muscle of the uterus, or to the fetus itself.

Another method involves real-time sonographic evaluation of the cervix.This method provides relatively quick and accurate cervical dimensions.However, it requires expensive equipment, highly skilled operators, aswell as skill in interpretation of results, which are all subject tohuman error. Additionally, there is a risk that the probe that must beinserted into the vagina as part of the procedure may cause injury ifnot inserted with care. Also, due to the expense of the procedure manywomen, especially those without proper health insurance, cannot affordto have a sonographic test performed.

It would be beneficial if there were an instrument a practitioner coulduse to measure the cervix quickly and accurately, and with littlematerial expense. Although there are several instruments available fordetermining various dimensions of the uterus, there is no suitableinstrument for measuring the length of the cervix in the formix vaginae.For example, U.S. Pat. No. 4,016,867 describes a uterine caliper anddepth gauge for taking a variety of uterine measurements, which althoughuseful for fitting an intrauterine contraceptive device, is not capableof measuring the length of the cervix in the formix vaginae due tointerference by the caliper's wings. In fact, similar devices describedin U.S. Pat. Nos. 4,224,951; 4,489,732; 4,685,474; and 5,658,295 sufferfrom similar problems due to their use of expandable wings ordivergeable probe tips. These devices are also relatively sophisticated,making them expensive to manufacture and purchase. U.S. Pat. No.3,630,190 describes a flexible intrauterine probe, which is particularlyadapted to measuring the distance between the cervical os and the fundusof the uterus. The stem portion of the device has a plurality of annularridges spaced apart from each other by a predetermined distance,preferably not more than one-half inch apart. However, this device isnot adapted for accurately measuring the length of the cervix in theformix vaginae because of the lack of an appropriate measuring scale anda stop for automatically recording the measurement.

There exists a need for a simple and inexpensive device that can be usedto determine the length of the cervix in the formix vaginae and, thus,predict the risk of preterm labor, as well as other conditions. There isalso a need for such a device that can measure the dilation of thecervix uteri, to provide an overall assessment of the cervix and todetermine the particular stage of labor. Ideally, the device should beadapted for use by a physician or obstetrician or even a trained nursein the doctor's office or clinic. Preferably, the device should besterile and disposable. In addition, it is desirable that device be ableto lock after a measurement is taken to ensure that the measurement doesnot change between the time a user takes the measurement and removes thedevice from the patient to read the measurement. The present inventionsatisfies these needs and provides related advantages as well.

SUMMARY OF THE INVENTION

In general, in one aspect, a device for measuring a length of a cervixincludes an elongate measurement member, a hollow member, a flange, ahandle, and a locking mechanism. The elongate measurement member extendsalong a longitudinal axis and includes a measurement scale thereon. Thehollow member is coaxial with and disposed over the elongate measurementmember. The flange is offset from the longitudinal axis and attached toa distal end of the hollow member. The handle is attached to a proximalend of the measurement member. The locking mechanism is configured, whenlocked, to fix the hollow member relative to the measurement member and,when unlocked to allow the hollow member to slide along the measurementmember and rotate about the longitudinal axis so as to place the flangein a desired position without moving the measurement scale.

This and other embodiments can include one or more of the followingfeatures. The proximal end of the hollow member can be slideable intothe handle. The flange can have an opening through which the measurementmember can advance distally. The flange can have a flat surfaceperpendicular to the longitudinal axis. The locking mechanism caninclude a button, the button including a through-hole configured suchthat the hollow member can slide therethrough and a lock channelconfigured such that the hollow member cannot slide therethrough. Thebutton can further include at least one lock ramp between thethrough-hole and the lock channel. The measurement scale can be amillimeter scale. The measurement scale can extend from 0 mm to 50 mm.The hollow member can be transparent. The measurement scale can includean opaque background. The device can further include an indicator lineon the hollow member. The indicator line can be a color other thanblack.

In general, in one aspect, a method for measuring a length of a cervixincludes: holding a handle of a device, the device further including anelongate measurement member having a measurement scale thereon, a hollowmember coaxial with and disposed over the elongate measurement member,and a flange attached to a distal end of the hollow member; rotating thehollow member about the elongate measurement member so as to place theflange at a desired orientation without rotating the measurement scale;advancing the device distally within a vagina until the flange contactsa cervix at an external uterine opening; advancing the measurementmember distally within the vagina until a distal end of the measurementmember contacts a cervical uterine junction at a formix vaginae; lockingthe measurement member relative to the hollow member by locking alocking mechanism on the handle; and observing a position of the hollowmember with respect to the measurement member to determine a length ofthe cervix in the formix vaginae.

This and other embodiments can include one or more of the followingfeatures. Advancing the measurement member distally can include slidingthe hollow member into the handle. The flange can be offset from alongitudinal axis of the measurement member. The locking mechanism caninclude a button having a through-hole and a lock channel, and whereinlocking the locking mechanism comprises pushing the button such that thehollow member moves into the lock channel and cannot slide through thethrough-hole. Observing the position can include observing an indicatorline on the hollow member with respect to a measurement scale on themeasurement member. The method can further include determining the riskof miscarriage based upon the length of the cervix in the formixvaginae, wherein the length of the cervix in the formix vaginae isinversely related to the risk of miscarriage. The method can furtherinclude predicting the ease of inducing labor, wherein the length of thecervix in the formix vaginae is inversely related to the ease ofinducing labor. The method can further include determining the risk ofpreterm labor based upon the length of the cervix in the formix vaginae,wherein the length of the cervix in the formix vaginae is inverselyrelated to the risk of preterm labor.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 a is an illustration of a measuring device, according to oneembodiment.

FIGS. 1 b-1 e are additional views of the measuring device of FIG. 1 a.

FIG. 2 a is an illustration of a measuring device, according to oneembodiment.

FIGS. 2 b-2 e are additional views of the measuring device of FIG. 2 a.

FIG. 3 a is an illustration of a measuring device, according to oneembodiment.

FIGS. 3 b-3 d are additional views of the measuring device of FIG. 3 a.

FIG. 4 a is an illustration of a measuring device, according to oneembodiment.

FIGS. 4 b-4 g are additional views of the measuring device of FIG. 4 a.

FIG. 5 a is an illustration of a measuring device, according to oneembodiment.

FIGS. 5 b-5 d are additional views of the measuring device of FIG. 5 a.

FIG. 6 a is an illustration of a measuring device, according to oneembodiment.

FIGS. 6 b-6 f are additional views of the measuring device of FIG. 6 a.

FIG. 7 a is an illustration of a measuring device, according to oneembodiment.

FIGS. 7 b-7 h are additional views of the measuring device of FIG. 7 a.

FIG. 8 is an illustration of a measuring device in use for measuring thevaginal cervix.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides various devices and methods fordetermining dimensions of female reproductive organs. For example, thedevices described herein are particularly adapted for determining thelength of the cervix in the formix vaginae, which, as described above,is related to the risk of preterm labor in an individual. The devicescan also be suited for determining the dilation of the cervix uteri, forpredicting the risk of preterm labor or the particular stage ofdelivery.

It is, however, contemplated herein, that the invention is not limitedto determining various dimensions of female reproductive organs. Forexample, the invention can be usable for determining the dimension ofany body cavity or passageway where such a device would be insertable,such as a vagina, uterus, mouth, throat, nasal cavity, ear channel,rectum, and also to any cavity created and opened by surgery, forexample, during chest, abdominal or brain surgery.

The devices described herein are also preferably fabricated fromrelatively inexpensive materials and the measurement is quick toperform. This allows the practitioner to repeat the test over time andtherefore to more closely monitor a woman's pregnancy and risk forpreterm labor. It is also contemplated that the device can record thevarious measurements automatically, where the only input required by thepractitioner is the proper insertion of the device into the body cavityor passageway. This can be accomplished by the use of a flange to stopprogression of the hollow member of the device while still allowing themeasurement member to be advanced within the body.

FIG. 1 a illustrates a measuring device 100 that includes an elongatedmeasurement member 102 and an elongated hollow member 104. The elongatedmeasurement member 102 is adapted to be inserted into the hollow member104, and specifically into a lumen of the hollow member. Handle 106 canbe positioned on a proximal portion of the measuring device, as shown inFIG. 1 a. In one embodiment, the handle is molded from the same materialas the measurement member 102. In other embodiments, the handle can be arubber or foam component that is fitted on to and over the proximal endof the measuring device.

A measurement scale 108 can be disposed along a portion of themeasurement member 102. The measurement scale 108 can include any numberof a series of visual markings on the measurement member 102 whichrelate a measurement or distance. In a particularly preferredembodiment, the measurement scale 108 includes a plurality of millimeter(mm) incremental markings and a plurality of centimeter (cm) incrementalmarkings.

As shown in FIG. 1 a, the measurement scale 108 can be color-coded toindicate the relative risks of preterm delivery for a cervix lengthfalling within each respective colored region. For example, in oneembodiment, a first zone 132 can include the incremental markings lessthan 2 cm and can be coded in a first color, such as red, a second zone134 can include the incremental markings from 2 to 3 cm and can be codedin a second color, such as yellow, and the third zone 134 can includethe incremental markings from 3 to 5 cm and can be coded in a thirdcolor, such as green. In FIG. 1 a, the measurement scale is color-codedinto three regions that each visually represents the relative risks ofpreterm delivery for a cervix length falling within the respectiveregion. For instance, the first zone 132 indicates a shorter cervix, andtherefore a higher risk of preterm delivery, than the second zone 134,which indicates a cervix length that reflects a higher risk of pretermdelivery than the green zone 136.

A flange 110 that is shaped for non-abrasive contact with tissue can bedisposed on a distal portion of measuring device 100. The flange can bepreferably flat and spherically or conically shaped. Alternatively,however, the flange may be any other non-abrasive shape to reduceirritation and scraping of the cervical canal, fundus of the vagina orperforation of the fundus of the uterus. The main body of the flange isalso preferably offset from the longitudinal axis of the measuringdevice 100. Additionally, the flange can include an opening 112 throughwhich measurement member 102 may be advanced distally after the flangecontacts a bodily surface. Preferably, the flange is secured to thedistal end of the hollow member 104 using a suitable attachment means,such as, e.g., an adhesive. Alternatively, the flange may be formed asan integral component of the hollow member 104.

FIGS. 1 b-1 d illustrate the operation of the measuring device 100 as itis used to measure the length of a cervix. When the distal end of themeasurement member 102 is flush with the flange, as shown in FIG. 1 b,the device is in a starting configuration. The device 100 can beadvanced into the vagina until the flange 110 is placed into contactwith the end of the cervix at the external uterine opening. At thispoint, further forward progress of the hollow member 104 within thecervical canal or further within the body is prevented as a result ofthe contact between flange 110 and the end of the cervix at the externaluterine opening. Since flange 110 is preferably offset from thelongitudinal axis of measuring device 100, in one embodiment the flangeis placed both in contact with the end of the cervix and also coveringthe external uterine opening. As a result, the device can oriented sothat measurement member 102 is still able to be progressed within theformix, rather than being advanced through the uterus, since the body offlange 106 is, with this method, covering the external uterine opening.

Subsequently, as shown in FIGS. 1 c-1 d, a distal portion of measurementmember 102 can continue to be advanced through opening 112 of flange 110until the distal end contacts a wall of the body, such as, e.g., theanterior formix. When the distal end of the measurement member isadvanced beyond the flange the device is in a measuring configuration.FIG. 1 c shows a side view of the measurement member in the measuringconfiguration, and FIG. 1 d shows a top down view of the device in themeasuring configuration. It can be seen in FIG. 1 d, for example, thatthe measurement member has been advanced 4 cm beyond the flange. Thelength of the cervix can then be measured by observing the position ofthe proximal end of the hollow member 104 along the measurement scale108 of the measurement member 102. In another embodiment, a method ofmeasurement comprises advancing the distal end of the measurement member102 to the wall of the body, such as the anterior formix, and thenadvancing the hollow member 104 so that the flange 110 is placed intocontact with the end of the cervix at the external uterine opening.

Referring now to FIG. 1 e, a locking mechanism 114 can be located on themeasuring device 100 that allows a user to secure the measurement member102 within the hollow member 104 after the measurement of a body part,such as, e.g., the length of the cervix. In FIG. 1 e, the lockingmechanism 114 includes button 116, cantilever arm 118, detents 120, andopening 122. When the locking mechanism is in the locked configuration,as shown in FIG. 1 e, the cantilever arm 118 engages detents 120 on theinside of hollow member 104. The cantilever arm can be integral to themeasurement member 102, for example. To allow sliding of the measurementmember within the hollow member, button 116 can be pressed inwardstowards opening 122, causing cantilever arm 118 to disengage detents 120and allow sliding.

For example, to take a measurement of a body part, a user can insert themeasuring device 100 into the patient. The user can then press thebutton 116 inwards to disengage the cantilever arm and allow themeasurement member to slide within the hollow member. After themeasurement of a body part is taken with the device, the user canrelease the button, causing the cantilever arm to engage the detents andlock the position of the measurement member 102 within the hollow member104. This allows the user to remove the device from the patient to readthe measurement scale while ensuring that movement of the measurementmember 102 proximally or distally within the hollow member 104 isprevented.

During a measurement procedure, a user can hold handle 106 with thedominant hand like a dart, and can hold the barrel of the hollow member104 with the non-dominant hand. The user can activate button 116 withthe dominant hand to temporarily unlock the measuring device, allowingthe hollow member to slide with respect to the measurement member.

Referring now to FIG. 2 a, another embodiment of a measuring device 200is shown. Measuring device 200 includes many of the features ofmeasuring device 100, described above and illustrated in FIGS. 1 a-1 e.For example, measuring device 200 includes an elongated measurementmember 202 slidably disposed within an elongated hollow member 204.Handle 206 can be positioned on a proximal portion of the measuringdevice, and measurement scale 208, such as a color-coded measurementscale, can be disposed on the measurement member 202. The measuringdevice can further include a flange 210 on a distal portion of thedevice, and an opening 212 that allows the measurement member 202 toextend distally beyond the hollow member 204.

As described above, the device 200 can have a starting configuration, asshown in FIG. 2 b, and a measuring configuration, as shown in FIG. 2 c.The measuring device 200 can further include a locking mechanism 214.The locking mechanism allows a user to lock the measurement member 202within the hollow member 204, to prevent movement of the measurementmember with respect to the hollow member after a measurement is taken.In the embodiment shown in FIGS. 2 a-2 e, the locking mechanism 214 isdisposed on the hollow member 204.

Referring now to FIG. 2 d, which is a side view of the locking mechanism214, and FIG. 2 e, which is a cross sectional view of the lockingmechanism 214, the locking mechanism can further include pads or buttons216, tabs 218, and detents 220. The buttons 216 and tabs 218 can beintegral to the hollow member 204, and the detents 220 can be integralto the measurement member 202, for example. In the embodiment shown inFIGS. 2 d-2 e, the locking mechanism includes two buttons 216. However,in other embodiments, the locking mechanism can include only a singlebutton, or alternatively, can include more than two buttons.

When the locking mechanism 214 is in a locked configuration, as shown inFIG. 2 d, the tabs engage detents 220, preventing any movement of themeasurement member with respect to the hollow member 204. However, whenthe buttons 216 are depressed inwards by a user, as shown in FIG. 2 e,the tabs 218 can be squeezed outwards, as indicated by arrows 224,causing them to disengage from detents 220. This allows a measurement tobe taken by sliding the measurement member 202 within the hollow member204.

To take a measurement of a body part, a user can insert the measuringdevice 200 into the patient. The user can then press the button orbuttons 216 inwards to cause the tabs 218 to squeeze outwardsdisengaging detents 220, thereby allowing the measurement member toslide within the hollow member. After the measurement of a body part istaken with the device, the user can release the buttons, causing thetabs to engage the detents and lock the position of the measurementmember 202 within the hollow member 204. This allows the user to removethe device from the patient to read the measurement scale while ensuringthat movement of the measurement member 202 proximally or distallywithin the hollow member 204 is prevented.

During a measurement procedure, a user can hold handle 206 with thedominant hand like a dart, and can hold the barrel of the hollow member204 with the non-dominant hand. The user can activate button 216 withthe non-dominant hand to temporarily unlock the measuring device,allowing the hollow member to slide with respect to the measurementmember.

Referring now to FIG. 3 a, yet another embodiment of a measuring device300 is shown. Measuring device 300 includes many of the features ofmeasuring device 100, described above and illustrated in FIGS. 1 a-1 e.For example, measuring device 300 includes an elongated measurementmember 302 slidably disposed within an elongated hollow member 304.Handle 306 can be positioned on a proximal portion of the measuringdevice, and measurement scale 308, such as a color-coded measurementscale, can be disposed on the measurement member 302. The measuringdevice can further include a flange 310 on a distal portion of thedevice, and an opening 312 that allows the measurement member 302 toextend distally beyond the hollow member 304.

As described above, the device 300 can have a starting configuration, asshown in FIG. 3 b, and a measuring configuration, as shown in FIG. 3 c.In addition, a locking mechanism 314 can be located on the measuringdevice 300 that allows a user to secure the measurement member 302within the hollow member 304 after the measurement of a body part, suchas, e.g., the length of the cervix.

In FIG. 3 d, the locking mechanism 314 includes button 316, cantileverarm 318, and detents 320. When the locking mechanism is in the lockedconfiguration, as shown in FIG. 3 d, the cantilever arm 318 engagesdetents 320 on the outside of measurement member 302. The cantilever armcan be integral to the hollow member 304, for example. To allow slidingof the measurement member within the hollow member, button 316 can bepressed inwards, causing cantilever arm 318 to disengage detents 320 andallow sliding.

For example, to take a measurement of a body part, a user can insert themeasuring device 300 into the patient. The user can then press thebutton 316 inwards to disengage the cantilever arm and allow themeasurement member to slide within the hollow member. After themeasurement of a body part is taken with the device, the user canrelease the button, causing the cantilever arm to engage the detents andlock the position of the measurement member 302 within the hollow member304. This allows the user to remove the device from the patient to readthe measurement scale while ensuring that movement of the measurementmember 302 proximally or distally within the hollow member 304 isprevented.

During a measurement procedure, a user can hold handle 306 with thedominant hand like a dart, and can hold the barrel of the hollow member304 with the non-dominant hand. The user can activate button 316 withthe non-dominant hand to temporarily unlock the measuring device,allowing the hollow member to slide with respect to the measurementmember.

Referring now to FIG. 4 a, another embodiment of a measuring device 400is shown. Measuring device 400 includes many of the features ofmeasuring device 100, described above and illustrated in FIGS. 1 a-1 e.For example, measuring device 400 includes an elongated measurementmember 402 slidably disposed within an elongated hollow member 404.Handle 406 can be positioned on a proximal portion of the measuringdevice, and measurement scale 408, such as a color-coded measurementscale, can be disposed on the measurement member 402. The measuringdevice can further include a flange 410 on a distal portion of thedevice, and an opening 412 that allows the measurement member 402 toextend distally beyond the hollow member 404.

As described above, the device 400 can have a starting configuration, asshown in FIG. 4 b, and a measuring configuration, as shown in FIG. 4 c.In contrast to the embodiments described above, the hollow member 404 ofthe measuring device 400 in FIGS. 4 a-4 e slides into the handle 406when a measurement is taken. The measurement member 402 remains fixed inposition with respect to the handle, which allows the measurement memberto extend distally beyond the flange 410 during measurements.

The measuring device 400 can further include a locking mechanism 414.The locking mechanism allows a user to lock the hollow member 404 withinthe handle 406, to prevent movement of the hollow member with respect tothe measurement member after a measurement is taken. In the embodimentshown in FIGS. 4 a-4 e, the locking mechanism 414 can comprise a button416 with a through-hole (not shown). In FIG. 4 d, the device is shown inan unlocked configuration, in which the through-hole is aligned with thehollow member 404 to allow the hollow member to travel therethrough.When the device is in a locked configuration, as shown in FIG. 4 e, thethrough-hole pushes against the hollow member, preventing movement ofthe hollow member with respect to the measurement member.

FIG. 4 f shows a cross-sectional view of locking mechanism 414, button416, and hollow member 404. The button geometry is designed to operatesmoothly with a low actuation force to engage the locking mechanism. Theopen channel 418 of the button allows the hollow member 404 to slidefreely into the handle when a measurement is being taken. When thebutton is depressed, the lock ramps 420 are forced to slide over thehollow member 404, which provides tactile and audible feedback that thedevice is in the locked position. The design of the lock ramps,including height and ramp angle affects the effort levels required toactivate the button. The width of the lock channel 422 is designed to benarrower than the overall outside diameter of the hollow member 404, sothat the interference between the two surfaces provides a retentionforce to maintain the measurement while the device is removed from thepatient. In some embodiments, the locking mechanism does not include thelock ramps 420. In other embodiments, the lock channel 422 can betapered to provide a frictional, locking fit for hollow member 404 whenbutton 416 is depressed, as shown in FIG. 4 g.

For example, to take a measurement of a body part, a user can insert themeasuring device 400 in an unlocked configuration (e.g., where thethrough-hole is aligned to allowed movement of the hollow member) intothe patient. After the measurement of a body part is taken with thedevice, the user can press the button 416, causing the through-hole topress against the hollow member to prevent movement of the hollowmember. This allows the user to remove the device from the patient toread the measurement scale while ensuring that movement of themeasurement member 402 proximally or distally within the hollow member404 is prevented.

During a measurement procedure, a user can hold handle 406 with thedominant hand like a dart, and can hold the barrel of the hollow member104 with the non-dominant hand. After taking a measurement, the user canactivate button 416 with the dominant hand to lock the measuring device,preventing the hollow member from sliding with respect to themeasurement member.

Referring now to FIG. 5 a, another embodiment of a measuring device 500is shown. Measuring device 500 includes many of the features ofmeasuring device 100, described above and illustrated in FIGS. 1 a-1 e.For example, measuring device 500 includes an elongated measurementmember 502 slidably disposed within an elongated hollow member 504.Syringe-style handle 506 can be positioned on a proximal portion of themeasuring device, and measurement scale 508, such as a color-codedmeasurement scale, can be disposed on the measurement member 502. Themeasuring device can further include a flange 510 on a distal portion ofthe device, and an opening 512 that allows the measurement member 502 toextend distally beyond the hollow member 504.

As described above, the device 500 can have a starting configuration, asshown in FIG. 5 b, and a measuring configuration, as shown in FIG. 5 c.Similar to the embodiment of measuring device 400 described above andillustrated in FIGS. 4 a-4 e, the hollow member 504 of the measuringdevice 500 in FIGS. 5 a-5 d slides into the handle 506 when ameasurement is taken. The measurement member 502 remains fixed inposition with respect to the handle, which allows the measurement memberto extend distally beyond the flange 510 during measurements.

The measuring device 500 can further include a locking mechanism 514.The locking mechanism allows a user to lock the hollow member 504 withinthe handle 506, to prevent movement of the hollow member with respect tothe measurement member after a measurement is taken. In the embodimentshown in FIG. 5 d, the locking mechanism 514 can comprise a button 516with a through-hole (not shown). Similar to the embodiments describedabove in FIGS. 4 a-4 e, the device can have an unlocked configuration,in which the through-hole is aligned with the hollow member 504 to allowthe hollow member to travel therethrough. The device can also have alocked configuration, in which the through-hole pushes against thehollow member thereby preventing movement of the hollow member withrespect to the measurement member.

To take a measurement of a body part, a user can insert the measuringdevice 500 in an unlocked configuration (e.g., where the through-hole isaligned to allowed movement of the hollow member) into the patient.After the measurement of a body part is taken with the device, the usercan press the button 516, causing the through-hole to press against thehollow member to prevent movement of the hollow member. This allows theuser to remove the device from the patient to read the measurement scalewhile ensuring that movement of the measurement member 502 proximally ordistally within the hollow member 504 is prevented. In FIG. 5 d, themeasurement scale is read at point 526 on the handle when taking themeasurement, for example.

During a measurement procedure, a user can hold syringe-style handle 506with the dominant hand like a syringe, and can hold the barrel of thehollow member 504 with the non-dominant hand. After taking ameasurement, the user can activate button 516 with the dominant ornon-dominant hand to lock the measuring device, preventing the hollowmember from sliding with respect to the measurement member.

Referring now to FIG. 6 a, another embodiment of a measuring device 600is shown. Measuring device 600 includes many of the features ofmeasuring device 100, described above and illustrated in FIGS. 1 a-1 e.For example, measuring device 600 includes an elongated measurementmember 602 slidably disposed within an elongated hollow member 604.Handle 606 can be positioned on a proximal portion of the measuringdevice, and measurement scale 608, such as a color-coded measurementscale, can be disposed on the measurement member 602. The measuringdevice can further include a flange 610 on a distal portion of thedevice, and an opening 612 that allows the measurement member 602 toextend distally beyond the hollow member 604.

As described above, the device 600 can have a starting configuration, asshown in FIG. 6 b, and a measuring configuration, as shown in FIG. 6 c.The measuring device 600 can further include a locking mechanism 614.The locking mechanism allows a user to lock the measurement member 602within the hollow member 604, to prevent movement of the measurementmember with respect to the hollow member after a measurement is taken.In the embodiment shown in FIGS. 6 a-6 f, the locking mechanism 614 isdisposed on the hollow member 204.

Referring now to FIG. 6 d, which is a cross sectional view of thelocking mechanism 614, the locking mechanism can further an annular snap628. The measurement member 602 also has an annular snap 630 thatcorresponds to the annular snap 628 on the locking mechanism. When thelocking mechanism is in an unlocked configuration, as shown in FIG. 6 d,the annular snaps 628 and 630 are not in contact, so there is some playbetween the locking mechanism 614 and the measurement member 602, whichallows the measurement member to slide freely within the hollow member604. As a user rotates the locking mechanism, as shown in FIG. 6 e, theannular snaps contact each other, providing the user with tactilefeedback of locking. In FIG. 6 f, the locking mechanism is shown in alocked configuration, with the annular snaps contacting each other onboth sides. When the annular snaps are in contact as shown in FIG. 6 f,there is no play between the hollow member and the measurement member,which prevents movement of the hollow member with respect to themeasurement member.

To take a measurement of a body part, a user can insert the measuringdevice 600 into the patient in the unlocked configuration. After themeasurement of a body part is taken with the device, the user can rotatethe locking mechanism 614, causing the annular snaps to engage eachother on both sides to lock the position of the measurement member 602within the hollow member 604. This allows the user to remove the devicefrom the patient to read the measurement scale while ensuring thatmovement of the measurement member 602 proximally or distally within thehollow member 604 is prevented.

During a measurement procedure, a user can hold handle 606 with thedominant hand like a dart, and can hold the locking mechanism 614 withthe non-dominant hand. After taking a measurement, the user can rotatethe locking mechanism with the non-dominant hand until the annular snapsengage each other to lock the measuring device, preventing the hollowmember from sliding with respect to the measurement member. The user canalso hold steady the locking mechanism 614 with the non-dominant handand rotate the handle 606 with the dominant hand until the annular snapsengage each other to lock the measuring device. The relative motion ofthe locking mechanism 614 and the handle 606 is what engages the lockingmechanism, regardless of which is held in place and which is rotated.

Referring now to FIG. 7 a, another embodiment of a measuring device 700is shown. Measuring device 700 includes many of the features ofmeasuring device 100, described above and illustrated in FIGS. 1 a-1 e.For example, measuring device 700 includes an elongated measurementmember 702 slidably disposed within an elongated hollow member 704. Themeasuring device can further include a flange 710 on a distal portion ofthe elongated hollow member 704, and an opening 712 that allows themeasurement member 702 to extend distally beyond the hollow member 704.Handle 706 can be positioned on a proximal portion of the measuringdevice and can be attached to the measurement member and measurementscale 708 can be disposed on the measurement member 702. As shown inFIG. 7 f, the measurement scale can be a millimeter sale, with markingsfrom 0-50 mm, marked in 5 mm increments. Moreover, the background 732for the measurement scale 708 can be opaque. For example, themeasurement member 702 can be composed of an opaque material or anopaque coating can cover the portion of the measurement member 702 onwhich the measurement scale 708 is printed. An opaque background for themeasurement scale can allow for easier readability of the numbers on thescale. Further, the hollow member 704 can be transparent and include anindicator line 734 that is colored, e.g., blue, to help contrast it fromthe measurement scale. Contrasting the indicator line 734 with themeasurement scale allows for easier readability of the finalmeasurement.

As described above, the device 700 can have a starting configuration, asshown in FIG. 7 b, and a measuring configuration, as shown in FIG. 7 c.Similar to the embodiment of measuring device 400 described above andillustrated in FIGS. 4 a-4 e, the hollow member 704 of the measuringdevice 700 in FIGS. 7 a-7 d slides into the handle 706 (or,alternatively, the handle 706 slides over the hollow member 704) when ameasurement is taken. The measurement member 702 remains fixed inposition with respect to the handle, which allows the measurement memberto extend distally beyond the flange 710 during measurements. As shownin FIGS. 7 g and 7 h, the elongated hollow member 704 can be free torotate with respect to the handle 706 and the measurement member 702(FIG. 7 g shows the flange 710 extending parallel to the page, whileFIG. 7 h shows the flange 710 extending out of the page). Such freerotation allows for the accommodation of any measurement technique, e.g.right or left-handed measurements, while still allowing for properplacement of the flange 710. That is, rotation of the hollow member 702to place the flange 710 in a desired position allows the measurementscale to remain in place, i.e., facing the user. Maintaining themeasurement scale directed towards the users ensures that the user ismore easily able to read and determine the measured length.

The measuring device 700 can further include a locking mechanism 714.The locking mechanism allows a user to lock the hollow member 704 withinthe handle 706, to prevent rotational or longitudinal movement of thehollow member with respect to the measurement member after a measurementis taken. In the embodiment shown in FIG. 7 d, the locking mechanism 714can comprise a button 716 with a through-hole (not shown). Similar tothe embodiments described above in FIGS. 4 a-4 e, the device can have anunlocked configuration, in which the through-hole is aligned with thehollow member 704 to allow the hollow member to travel therethrough. Thedevice can also have a locked configuration, in which the through-holepushes against the hollow member thereby preventing movement of thehollow member with respect to the measurement member.

To take a measurement of a body part, a user can hold the handle 706with the dominant hand and can hold the hollow member 704 with thenon-dominant hand. The user can orient the measuring scale 708 such thatit faces the user and can then rotate the hollow member 704 such thatthe flange 710 is properly oriented with respect to the patient. Becausethe hollow member 704 is transparent, the measuring scale 708 can beviewed through the hollow member 704.

The measuring device 700 can be inserted in an unlocked configuration(e.g., where the through-hole is aligned to allowed movement of thehollow member) into the patient. After the measurement of a body part istaken with the device, as described above, the user can press the button716, causing the through-hole to press against the hollow member toprevent movement of the hollow member. This allows the user to removethe device from the patient to better read the measurement scale whileensuring that movement of the measurement member 702 proximally ordistally within the hollow member 704 is prevented.

Referring to FIG. 8, the devices described herein can be used to measurethe vaginal cervical length. The flange 810 (representing any of theflanges described herein) can be placed against the proximal wall ofcervix 802, while the measurement member 702 (representing any of themeasurement members described herein) can be extended along the lateralwall of the cervix 802 until it is stopped by the vaginal formix 804.The measurement member 702 and the flange 810 can then be locked withrespect to one another such that the device's measurement scale can beused to determine the length as described above.

As for additional details pertinent to the present invention, materialsand manufacturing techniques may be employed as within the level ofthose with skill in the relevant art. The same may hold true withrespect to method-based aspects of the invention in terms of additionalacts commonly or logically employed. Also, it is contemplated that anyoptional feature of the inventive variations described may be set forthand claimed independently, or in combination with any one or more of thefeatures described herein. Likewise, reference to a singular item,includes the possibility that there are plural of the same itemspresent. More specifically, as used herein and in the appended claims,the singular forms “a,” “and,” “said,” and “the” include pluralreferents unless the context clearly dictates otherwise. It is furthernoted that the claims may be drafted to exclude any optional element. Assuch, this statement is intended to serve as antecedent basis for use ofsuch exclusive terminology as “solely,” “only” and the like inconnection with the recitation of claim elements, or use of a “negative”limitation. Unless defined otherwise herein, all technical andscientific terms used herein have the same meaning as commonlyunderstood by one of ordinary skill in the art to which this inventionbelongs. The breadth of the present invention is not to be limited bythe subject specification, but rather only by the plain meaning of theclaim terms employed.

1. A device for measuring a length of a cervix, comprising: an elongatemeasurement member extending along a longitudinal axis and including ameasurement scale thereon; a hollow member coaxial with and disposedover the elongate measurement member; a flange offset from thelongitudinal axis and attached to a distal end of the hollow member; ahandle attached to a proximal end of the measurement member; and alocking mechanism configured, when locked, to fix the hollow memberrelative to the measurement member and, when unlocked, to allow thehollow member to slide along the measurement member and rotate about thelongitudinal axis so as to place the flange in a desired positionwithout moving the measurement scale.
 2. The device of claim 1, whereina proximal end of the hollow member is slideable into the handle.
 3. Thedevice of claim 1, wherein the flange has an opening through which themeasurement member can advance distally.
 4. The device of claim 1,wherein the flange has a flat surface perpendicular to the longitudinalaxis.
 5. The device of claim 1, wherein the locking mechanism includes abutton, the button including a through-hole configured such that thehollow member can slide therethrough and a lock channel configured suchthat the hollow member cannot slide therethrough.
 6. The device of claim5, wherein the button further comprises at least one lock ramp betweenthe through-hole and the lock channel.
 7. The device of claim 1, whereinthe measurement scale is a millimeter scale.
 8. The device of claim 1,wherein the measurement scale extends from 0 mm to 50 mm.
 9. The deviceof claim 1, wherein the hollow member is transparent.
 10. The device ofclaim 1, wherein the measurement scale includes an opaque background.11. The device of claim 1, further comprising an indicator line on thehollow member.
 12. The device of claim 11, wherein the indicator line isa color other than black.
 13. A method for measuring a length of acervix, comprising: holding a handle of a device, the device furthercomprising an elongate measurement member having a measurement scalethereon, a hollow member coaxial with and disposed over the elongatemeasurement member, and a flange attached to a distal end of the hollowmember; rotating the hollow member about the elongate measurement memberso as to place the flange at a desired orientation without rotating themeasurement scale; advancing the device distally within a vagina untilthe flange contacts a cervix at an external uterine opening; advancingthe measurement member distally within the vagina until a distal end ofthe measurement member contacts a cervical uterine junction at a formixvaginae; locking the measurement member relative to the hollow member bylocking a locking mechanism on the handle; and observing a position ofthe hollow member with respect to the measurement member to determine alength of the cervix in the formix vaginae.
 14. The method of claim 13,wherein advancing the measurement member distally comprises sliding thehollow member into the handle.
 15. The method of claim 13, wherein theflange is offset from a longitudinal axis of the measurement member. 16.The method of claim 13, wherein the locking mechanism includes a buttonhaving a through-hole and a lock channel, and wherein locking thelocking mechanism comprises pushing the button such that the hollowmember moves into the lock channel and cannot slide through thethrough-hole.
 17. The method of claim 13, wherein observing the positioncomprises observing an indicator line on the hollow member with respectto a measurement scale on the measurement member.
 18. The method ofclaim 13, further comprising determining the risk of miscarriage basedupon the length of the cervix in the formix vaginae, wherein the lengthof the cervix in the formix vaginae is inversely related to the risk ofmiscarriage.
 19. The method of claim 13, further comprising predictingthe ease of inducing labor, wherein the length of the cervix in theformix vaginae is inversely related to the ease of inducing labor. 20.The method of claim 13, further comprising determining the risk ofpreterm labor based upon the length of the cervix in the formix vaginae,wherein the length of the cervix in the formix vaginae is inverselyrelated to the risk of preterm labor.